of cleveland



March 12, 1929. w. k. DAY 1,704,700

PISTON AND PISTON RING Filed Dec. 13, 1924 INVENTOR ATTORNEY PatentedMar. 12, 1929.

UNITED STATES PATENT OFFICE.

WILLIAM R. DAY, OF CLEVELAND, OHIO, ASSIGNOR TO THE GUARDIAN TRUST COK-PANY, TRUSTEE, OF CLEVELAND, OHIO, A CORPORATION OF OHIO.

PISTON AND PISTON RING.

Application filed December 13, 1924. .Serial No. 755,610.

My invention relates to piston and pistonring structures.

In this specification and in the claims appended thereto, I use theexpressions compressed gas and pressure and means thereby eithercompressed air, or compressed fuel gas, or steam, or other gas or othersubstances suitable for use in any particular or general engine unlessthe nature of the gas 15 definitely set forth. I also use the expressionfgas and mean thereby either of the gases and substances set forthabove.

One of the objects of my invention is a p15- ton and piston-ringstructure in which no spring means is required in or on the pistonrm Another object is to force a piston-ring onto the wall of a cylinder inwhich the ring operates by the pressure of the gas in this cylinder andto limit the pressure of this gas on the piston-ring to avoidunnecessary friction.

Another object is to force a piston-ring onto the side walls of thepiston groove in which the piston-ring operates by the pressure of thegas or by a vacuum in the cylinder in which the piston operates.

Another ob ect is to provide a split pistonring with a joint which issealed by pressure or by vacuum in the cylinder in which the piston-ringoperates.

Another object is a piston and piston-ring structure which effectivelyseals the piston against high pressures in a cylinder.

Another object is a piston and piston-ring structure which effectivelyseals the piston 1n a cylinder without creating unnecessary frictionbetween the ring and the cylinder wall.

Broadly speaking, the present invent on aims to provide a piston andpiston-rmg structure which seals the piston in a cylinder by utilizingthe pressure in this cylinder, either partly or wholly, to press thepistonring against the Wall of this cylinder and against the walls ofthe iston-ripg groove in the piston with just su cient force to preventleakage and without creating unnecessary friction between thepiston-ring and the wall of this cylinder.

My invention is illustrated in the accompanying drawing which shows twotypes of piston and piston-ring structures and in which Fig. 1 is aperspective view of a piston with one piston-ring mounted therein,embodying the features of my invention, and partly in section to clearlyshow the section of the piston-ring and the expansion chamber and therelation of the piston-ring to the piston and to this expansion chamber.

Fig. 2 is a perspective view of one section of a three piecepiston-ring, showing the lap joints thereof in relation to the body partthereof.

Fig. 3 is a perspective view of a piston with one piston-ring mountedtherein, also em bodying the features of my invention, partly in sectionto clearly show the section of the piston-ring and the relation thereofto the piston.

Similar reference characters refer to similar parts throughout theviews.

Referring now particularly to Fig. 1. The piston A is here shown withone piston-ring groove having the Walls 10 and 11. The upper end of thepiston is reduced in diameter, thereby providing the recessed wall 12.The expansion chamber 13 is recessed in this wall 12 and, in the presentinstance, extends all the way around this reduced end of the piston.

The piston-ring used here is made in three sections, one of the sectionsis shown in Fig. 2, each section is a duplicate of the others. and thethree sections are formed and jointed to virtually constitute a completepiston ring.

The structure shown in Fig. 3 is similar to that shown in Figs. 1 and 2except that the expansion chamber 13 is absent in Fig. 3. Therefore, theexplanation of the iston-ring structure of Figs. 1 and 2 also app y toFig. 3.

This jointed piston-ring comprises the body portion 14 and the flangeportion 15 which is tubular and extends upward from the portion 14.

One end of each section of the piston-ring is provided or formed with arecess in the body or base portion 14 thereof thereby leaving the lap 16on this end. The other end is provided or formed with the projection 17of approximately the same size as the recess on the opposite end. Whenthe three sections are assembled, the lap 16 of one section is disposedover the projection 17 of the adjacent section as seen in Figs. 1 and 3.

When the piston-ring 1S assembled in the piston, the flange 15 is spacedfrom the wall 12 to provide the space 22 ending in the port 18 at theupper end of the ring. The flange 15 extends up to the end of the wall12 in Fig. 1 while this flange extends not uite to the end of the wall12 in Fig. 3. The isposition of the end of the flange 15 in relation tothe end of the wall 12 is bestdetermined by requirements of anyparticular piston and the pressure in the cylinder.

As seen in Fig. 1, the expansion chamber 13 does not extend way donn tothe wall 10, thereby providing the toe 1S and preserving the full widthof the wall 10.

The structure shown in Figs. 1 and 3 can be applied to explosiveengines, or oil burning engines, or steam engines, or other pressure onines which have parts similar to piston an piston-rings and which partsneed sealing.

As to general operation ol the structure shown and described :---ll henthe piston and piston-ring shown is inserted into the cylin der B, thepiston ring rests lightly on the wall oi the cylinder with practicallyno friction between this well and the ring as long as the engine runsidle.

When a ressure exists in the cylinder, above the piston, some of thispressure enters the port 18 and fills the space 232 this prcssu rc thenforces the rin sections outward against the well of the cylinder toprevent leakage there.

1n gas explosion engines, as well as in fuel burning engines, a veryhigh pressure is created above tlie piston at certain stages oi thestroke which high pressure would force the ring sections against thecylinder wall with sufiicient force to create too much friction there itnot regulated and thereby practically act as a brake.

In order to prevent this high friction, I proportion the port 18 so thatonly a small quantity ot this high pressure enters the space 2:2. Afterthis high pressure has passed the port 18, it enters th expansionchamber 13, thereby reducing the pressure against the inner surface ofthe firings 15.

It is observed heir: that, in addition to restricting the adinii-ision.of the pressure through the port it), the inner urea oi. the flange 15con also bi so proportioned that the ring sections can bi forced or heldagainst the cylinder w all with any desired -iorce. For instance, it it.desired that the ring sections are to he held nguinst the ('3 lindcrwall with a torcc of ten pounds and the presto re in the cylinder istwenty pounds, the urea oi the inner surince of the hinge should heonchell oi the arcs of the outer suifece ot the pistonring ThisllltlSiIfltlOIl is, of course. rough only and not strictly in compliancewith en' gineering rules but is nnzntioned here only to convey my idesoi proportioning the pistonring to get best results. This propottioningof the piston-ring can also be carried out effectively withoutrestricting or otherwise act ing on the pressure either while the sameenters the port 18 or thereafter.

Taking a concrete example to explain the action of my piston andpiston-ring struc ture, I will describe this action as it takes place ina gas explosion engine; it being understood that the present piston andpiston ring structure acts in a similar manner in other engines.

lit a four cycle gas explosion engine we have a suction stroke, acompression stroke, and a power stroke.

"hen the piston first moves downward on the suction sti-olie, there issufiicient pressure in the combustion chamber to hold. the piss ton-ringsections against the cylinder wall. Due to the friction between thepistonwing and the cylinder wall,the portion 14 of the rin is forcedagainst the wall of the groove in t is piston, thereby sealing the jointthere. The partial vacuum created in the cylinder by this suction strokeextends into the space 22 and thereby exerts a suction action on thehuge and en the face 20. Since the flange 15 bears against the cylinderwall without any air therebetw'een, this suction action has no effect onthe piston-ring radially but, since the face 21 is now relieved from thewall 11, this suction action helps to hold thebody 14 against the face10, thereby effectively scaling the piston on the suction stroke.

When the piston first starts to move up ward on the compression stroke,there is precticslly no pressure in the cylinder. As soon the piston.starts to move 11 .-Ward, pressure is erected in the cylinder w ichpressure is very light at first and continues to increase as the pistontrevels upward. This compres sion. pressure in the cylinder is formedgruduzilly during the entire upward movement of the piston. and givesthis pressure suilicicnt time to enter the space gradually and therebyforces the ing sections against the well ot the cylinder with nothingmore than the force exerted thereon by this gradually in creasingpressure, thereby sealin the pist. on the cylinder wall without unduepros. and without creating more friction than lltit essary= lt notedhere that the port- 18 may also he proportioned so that the full finalcompress sion pressure does not act on the piston-riug hen so desired.

When the piston is so moving upward on the compression stroke, thefriction between the flange 15 end the well of the cylinder forces thebody 14 of the ring onto the well 11 oi the ginove in the piston and, ineddition thereto, the increasing pressure in the cylinder acts on theface as well as on the square end of the flange 15, thereby furtherholding the body 14; onto the wall 11 and pro duciug an. effective sealthere.

lli

lap 'oint.

hen the piston is at the beginning of its power stroke, the compressedgas explodes and thereby suddenly increases the pressure in thecylinder. If noprovision is made to exclude this increased pressure fromthe inside of the piston-ring, the ring sections'will be forced againstthe cylinder wall with more force than necessary and thereby createunnecessary friction and decrease the efliciency of the engine.

In the present invention, the port 18 is just sufficiently large toadmit suflicient pressure to thespace 22 to press the ring sectionsagainst the cylinder wall with the desired pressure but is notsufliciently large to instantly admit the full explosion pressure tothisspace as previously explained. Therefore, before this high pressure canfill the space 22, the piston has traveled some distance and therebydecreased the pressure in the cylinder before this highpressure has achance to act on the ring sections with its full force.

The principle explained in the last paragraph, 1-n connection with thehigh pressure, can also be carried out in the same manner in connectionwith the compression pressure. As is well known, the compressionpressure increases very rapidly toward the end of the compressionstroke, therefore, the port 18 can be proportioned so that the fullfinal compression pressure does not act on the piston-ring sections.

When the space 22, as shown in Fig. 3, is not suflicient to reduce thepressure on the ring sections to a desired de ree, I introduce theexpansion chamber 13 Fig. 1) in connection with the space 22 and withthe port 18. In this instance, the port 18 and the space 22 accomplishthe same purposes as previously explained and the chamber 13 1s added torovide more volume to the space 22 so'that t e piston will travelfurther before the pressure in the space 22 and in the chamber 13 isequal to the pressure in the cylinder. By the time the piston hastraveled far enough to so equalize the pressure, the higher pressuresfirst created m the cylinder, either by explosion or .by compression,have expanded and are not now sufliciently great to force the ringsections against the cylinder wall with unnecessary pressure.

Although the port 18 is shown of the same width as the space 22, it isunderstood that this port may be narrower than the space 22 or may berestricted in area in other manners.

It is observed that the present invention provides a piston andpiston-ring structure in which the piston-rin sections are forcedagainst a cyhnder wall with a force equal to the pressure in thecylinder at some stages of the travel of the piston and with less thanthe pressure in the cylinder at other stages of this travel of thepiston.

The present invention seals a piston in a cylinder against highpressures and does so without creating unnecessary friction between thepiston ring and the cylinder wall.

I am'aware that pistons have been made with reduced ends and withpiston-rings having a flange disposed over this reduced end; therefore,I do not claim such feature broadly but I do claim the improvementsthereon as set forth in this specification andincluded in the claimsappended thereto.

I am also aware that modifications, other than those shown and describedand pointed out, may be made within the scope of the appended claims;therefore, without limiting myself to the precise construction andarrangement of elements shown and described and pointed out,

I claim 1. A cylindrical member and a member to be sealed therein, aring mounted in said member to be sealed and radially expansible bymeans of fluid pressure, a portion of said ring spaced from said memberto be sealed, one end of said space being open, and said open endproportioned to limit the quantity of fluid pressure admitted into saids ace.

2. In combination, a piston provi ed with a reduced end and with a ringgroove adjacent this reduced end and with an expansion chamber in thisreduced end, and a radially split piston-ring comprising a body portiondisposed in said groove and a flange portion disposed over said reducedend and therefrom radiall 3. In combination, a cylinder, a piston insaid cylinder and provided with a reduced end and with a ring grooveadjacent this reduced end and an expansion chamber in this reduced end,a radially split piston-ring comprising a body portion disposed in saidgroove and a flange portion disposed over said reduced end and spacedtherefrom radially to form a chamber open at the outer end of saidreduced end, and said open end of the chamber adapted to admit the fullpressure of said cylinder into said chamber at some stages of the travelof the iston and less than this full pressure at ot er stages of thistravel.

4. In combination, a cylinder, a piston in said cylinder and providedwith a recessed portion and with a ring groove adjacent this recessedportion and with an expansion chamber in this recessed portion, aradially split piston-ring comprising a body portion disposed in saidgroove and a flange portion disposed over said recessed portion andspaced therefrom radially to augment said expansion chamber, and ortmeans for admitting the full pressure rom said cylinder into spaced saidchamber at some stages of the travel of said piston and less than fullpressure at other stages of this travel.

5. In combination, a cylinder, a piston in said cylinder and providedwith a ring groove, a piston-ring mounted in said ring move and dividedradially into sections havmg 0 posite ands lapped over each other, a

cham er between said piston-ring and said piston, and port means forsaid chamber and 10 proportioned to admit sufiicient pressure from saidcylinder into said chamber to seal said piston in said cylinder and toseal said piston-ring in said ring groove and to seal said lap jointswithout creating unnecessary l5 friction between said piston-ring andthe wall of said cylinder.

WILLIAM R. DAY.

